The present invention relates to a scanning atomic force microscope for observing the topography of a specimen surface by making use of an atomic force exerted between substances.
The prior art scanning atomic force microscope uses a probe comprising a cantilever and a probe portion formed over the cantilever which is made of silicon nitride or silicon. The atomic force exerted between the probe portion and the specimen surface is detected as a deflection of the cantilever, a change in the amplitude of the vibration, or a change in the resonance frequency. The probe tip and the specimen are moved relative to each other while maintaining the distance between them constant. Thus, the specimen surface is observed. In this case, it is common practice to utilize an optical procedure for detecting the displacement of the cantilever. Where such an optical procedure is employed, the instrumentation is complicated. Furthermore, various adjustments such as adjustment of the optic axis are necessary. Hence, it has been complex and laborious to handle the instrument.
In connection with them, a cantilever incorporating a piezoelectric detection mechanism for electrically detecting vibrations is described in Japanese Patent Unexamined Publication No. 196458/1993. Also, AFM (atomic force microscope) probes using quartz oscillators have been proposed in Japanese Patent Unexamined Publication Nos. 309803/1988 and 102008/1992.
In the case of the above-cited Japanese Patent Unexamined Publication No. 196458/1993 where displacements of the cantilever are electrically detected without using any optical procedure, a process for forming a thin piezoelectric film is involved. Therefore, the fabrication of the probe is complicated.
In the quartz oscillator probe described in the Japanese Patent Unexamined Publication No. 309803/1988, the quartz oscillator adheres to the probe portion together. This structure is not easy to manufacture. The quartz oscillator probe described in the Japanese Patent Unexamined Publication No. 102008/1992 is not associated with electrical detection. Moreover, no detailed description is made of the fabrication. Accordingly, a method of easily fabricating an atomic force microscope (AFM) probe using a quartz oscillator and a scanning atomic force microscope which is easy to handle have been sought for.
Furthermore, in the AFM probe, sharpening of the probe tip presents problems. Accordingly, it is an important object to provide a method of sharpening the tip.